1. Field of the Invention
This invention relates to a method for cooling a semiconductor device.
2. Background Art
A semiconductor element constituting a semiconductor device runs away at increased temperature. Hence the semiconductor element is controlled to less than a prescribed temperature for safe operation. In particular, a highly heat-generating semiconductor chip dissipates heat with a heat spreader (heat spreading plate), a heat sink (heat radiating plate), and/or a fan. For example, the upper face of the semiconductor element is covered with a heat spreader, and a heat sink is further mounted thereon to improve heat dissipation characteristics. Some products use water cooling techniques.
In any cooling techniques, cooling is performed by thermally connecting a heat receiving portion to the upper face of the semiconductor element. However, small electronic devices such as mobile phones are slimmed down, leaving insufficient space above the semiconductor element. Consequently, it is expected that cooling becomes difficult.
As a conventional technique, JP 2000-164777A discloses a semiconductor device with a heat radiating plate made of graphite fibers arranged in the planar direction and extending in the plate thickness direction, thereby allowing reduction of thermal resistance. A heat spreading member made of copper plate is laminated on the entire surface of the heat radiating plate made of graphite fibers arranged in the planar direction and extending in the plate thickness direction. A semiconductor chip is die-bonded at the upper side center of the heat spreading member, and external terminals are held with ceramic material at the upper edge of the heat spreading member. The heat spreading member is electrically insulated from the external terminals by the ceramic material, and the semiconductor chip is electrically connected to the external terminals by bonding wires. In this case, the thickness of the semiconductor device increases, as the semiconductor chip and the heat radiating plate are stacked.